Molecular Biology/Genetics USMLE Step 1 Practice Question
A 29-year-old woman with family history of Huntington disease presents for genetic screening. Vital signs are stable (BP 118/76, HR 72, RR 14, Temp 37°C). She reports no current neurological symptoms or involuntary movements. Genetic counseling reveals three affected relatives. Her physician orders a laboratory method to detect and precisely size the expanded CAG trinucleotide repeat directly within her genomic DNA. Which technique best accomplishes this molecular analysis?
Answer choices
- AFlow cytometry
- BWestern blot
- CELISA
- DNorthern blot
- ESouthern blotCorrect answer
- FPCR-based sequencing with next-generation platforms
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